Vitamin K-dependent coagulopathy in a child receiving anticonvulsant therapy

Valproate-associated coagulopathies in children during short-term treatment

Valproic acid is one of the most frequently prescribed antiepileptic drugs for the therapy of generalized and focal epilepsies. Valproate induces a variety of hemostatic disorders such as thrombocytopenia, abnormal platelet function, hypofibrinogenemia, and decreased concentrations of von Willebrand factor, and it rarely causes serious bleeding complications. It may also lead to atherosclerosis and thrombosis. However, there is still lack of knowledge about the incidence and occurrence of these particular side effects. In this prospective systematic study, we assessed the early effects of sodium valproate on both pro- and anticoagulatory factors, homocysteine, and lipoprotein (a) in 24 newly diagnosed epileptic children treated with valproate. Valproate causes decreased factor VII levels, platelet count, factor VIII, Protein C, fibrinogen, and increased lipoprotein (a) levels. To the best of our knowledge, our report is the first in the medical literature, which describes that valproate significantly reduces factor VII levels even during short-term therapy.

Valproate-associated coagulopathies are frequent and variable in children

PURPOSE

Valproic acid (VPA) is an antiepileptic drug (AED) commonly used for generalized and focal epilepsies. The clinical relevance of coagulopathies, known as side effects of VPA therapy, especially thrombocytopenia, von Willebrand disease, and a decrease of factor XIII, is still unclear.

METHODS

In our institute, we noticed a high incidence of clinically relevant coagulation problems related to VPA in eight patients within 1 year only and a further seven children with significant coagulopathy were identified in the context of planned surgery.

RESULTS

We provide an overview of these patients and all six VPA-induced coagulopathies.

CONCLUSIONS

At this time, it cannot be recommended to control all hemostatic parameters in every patient. Whenever an increased bleeding tendency is observed, or before surgical procedures, a platelet count, thrombelastography, prothrombin time, activated partial thromboplastin time, TT, fibrinogen, von Willebrand factor, and factor XIII should be examined. With 385 VPA-treated patients per year and 15 cases of coagulation disorders in this period, we estimate the incidence of coagulation disorders related to VPA in children to be nearly 4%.

Vitamin K deficiency in children pre-bone marrow transplantation

This study examined the prevalence of vitamin K deficiency in children pre-bone marrow transplantation (BMT). Vitamin K status was measured by the PIVKA-II assay and prothrombin times. Blood samples were obtained before vitamin-containing TPN was infused. Results indicated that eight of 26 patients (31%) were vitamin K deficient; four cases were attributed to drug antagonism (phenytoin) and four were due to inadequate vitamin K intake, synthesis or malabsorption. Only one patient had a prolonged prothrombin time. Prothrombin time, in our study, is shown to be an ineffective screening tool to determine vitamin K status. All patients receiving phenytoin and chemotherapy are at increased risk of vitamin K deficiency.

Predictors of red cell transfusion in children and adolescents undergoing spinal fusion surgery

STUDY DESIGN

A retrospective review was performed.

OBJECTIVE

To determine clinical predictors of allogeneic and autologous red cell transfusion in children and adolescents undergoing spinal fusion surgery.

SUMMARY OF BACKGROUND DATA

Blood loss during spinal fusion surgery often results in the need for transfusion therapy. Preoperative identification of patients at increased risk for red cell transfusion would allow more specific use of interventions designed to control excessive bleeding.

METHODS

The medical records of all patients undergoing posterior spinal fusion surgery at a single institution between July 1, 1999 and June 30, 2001 were reviewed. Logistic and stepwise multiple regression analyses were used to identify predictors of allogeneic and autologous red cell transfusion during the operative and postoperative periods.

RESULTS

Posterior spinal fusion surgery was performed in 107 patients (males, 42%) with a median age of 13.7 years (range, 1-20 years). The median intraoperative blood loss was 22 mL/kg (range, 4.4-72 mL/kg). Blood transfusion involved 63 patients (59%) who received 17 mL/kg (range, 3-65 mL/kg) of allogeneic packed red blood cells and 14 patients (13%) who received 7 mL/kg (range, 4-19 mL/kg) of autologous red cells donated before surgery. Underlying neuromuscular disease, lower body weight, and a higher number of vertebrae fused independently predicted a greater number of allogeneic red cells transfused (R2 = 0.53). The amount of autologous blood donated before surgery predicted the number of autologous red cells transfused (R2 = 0.56).

CONCLUSIONS

Allogeneic red cell transfusion often is required for small patients with underlying neuromuscular disease who undergo extensive spinal fusion surgery. These patients may be less able to donate autologous blood before surgery. Newer therapies to reduce blood loss and transfusion requirement are needed most for this population.

Bleeding and coagulation changes during spinal fusion surgery: a comparison of neuromuscular and idiopathic scoliosis patients

OBJECTIVE

Major blood loss is common during spinal fusion surgery. We have previously demonstrated that patients with neuromuscular scoliosis have more blood loss and greater transfusion requirement than those with idiopathic scoliosis. Our objective is to study the relationships between etiology of scoliosis, blood loss, and coagulation changes in children and adolescents undergoing spinal fusion surgery.

DESIGN

Prospective, observational study.

SETTING

University teaching hospital.

PATIENTS

A total of 25 patients, 11 with neuromuscular and 14 with idiopathic scoliosis, undergoing spinal fusion surgery.

INTERVENTIONS

Blood was obtained preoperatively, 2 and 4 hrs intraoperatively, and 2 and 24 hrs postoperatively for prothrombin time, partial thromboplastin time, thrombin time, platelet count, D-dimer, factor VII and VIII activity, thrombin-antithrombin III complex, and protein induced by vitamin K absence. Changes in coagulation over time were analyzed by repeated-measures analysis of variance. Comparisons between groups were made using independent t-tests.

RESULTS

Neuromuscular scoliosis patients had significantly greater blood loss than idiopathic scoliosis patients (median blood loss, 78% of total blood volume; range, 25-127% vs. 20%, 2-82%; p < .001). Prothrombin time increased over time in both groups and was higher in the neuromuscular than the idiopathic group both preoperatively and postoperatively (p < .05). Factor VII activity decreased over time in both groups (p < .001) and was lower in the neuromuscular than the idiopathic group during surgery (p < .05). No changes in partial thromboplastin time, thrombin time, or factor VIII activity were observed. D-dimers were present in both groups by 4 hrs intraoperatively. Protein induced by vitamin K absence was not detected in any patient.

CONCLUSIONS

Neuromuscular scoliosis patients have more blood loss during spinal fusion surgery than idiopathic scoliosis patients. The prolongation of prothrombin time and decrease in Factor VII activity suggest activation of the extrinsic coagulation pathway. Depletion of clotting factors during scoliosis surgery occurs to a greater extent in patients with underlying neuromuscular disease.